Document Type

Article

Publication Date

4-4-2016

Publication Title

The Journal of Physical Chemistry

Volume

120

Issue

16

First page number:

8607

Last page number:

8615

Abstract

The complex electronic structure of ordered 3,4,9,10-perylene tetra carboxylic acid dianhydride (PTCDA) multilayers on Ag(111) is investigated by angle-dependent resonant X-ray emission spectroscopy at the carbon K edge. Beam damage effects were characterized and special care was taken to avoid their influence on the spectra. Appropriate selection of excitation energies and detection geometries allow us to record element-, atom-, and symmetry-specific X-ray emission spectra by making use of dipole selection rules. This specificity, especially the ability to distinguish between σ and π orbitals, gives unprecedented experimental insights into the electronic structure of this large organic molecule. The experimental results are compared with calculated spectra of the isolated molecule, as derived from density functional theory. This allows a detailed discussion of the spectra and separation of the contributions from nonequivalent carbon atoms.